docs: def parametrize(params):
      """Return list of params as params.
  
      >>> parametrize(['a'])
      'a'
      >>> parametrize(['a', 'b'])
      'a[b]'
      >>> parametrize(['a', 'b', 'c'])
      'a[b][c]'
  
      """
      returned = str(params[0])
      returned += "".join("[" + str(p) + "]" for p in params[1:])
      return returned